The present invention relates generally to building construction techniques and more particularly to methods of constructing building partitions such as walls, ceilings and the like. The invention has been developed primarily for use in wall construction and will be described herein with reference to this use. However, it will be appreciated that the invention can be applied to other similar structures such as floors, ceilings and fences etc.
In conventional modern housing construction, walls are generally fabricated by first erecting a structural frame, which is typically formed from timber. The frame is lined internally with a suitable lining material such as plaster board or fibre reinforced cement sheeting, which is subsequently finished to conceal joints and finally painted. The external wall is traditionally formed from brick veneer or masonry which provides the advantages of strength, durability and resistance to adverse weather conditions in a relatively cost effective manner. A particular advantage of masonry construction is the look and feel of solidity, which many home owners find desirable.
In the past, alternative external cladding materials have also been used. These include timber weatherboards, roll formed aluminium panels, as well as fibre reinforced cement sheets, planks and boards in various surface textures and finishes. These materials have been found to be generally competitive with brick veneer construction on a cost basis. However, a major disadvantage is that such cladding materials do not exhibit the same strength, impact resistance, and feel of solidity as masonry. In particular, they produce a hollow xe2x80x9cdrummngxe2x80x9d sound when knocked, which tends to convey a subjective perception of insubstantiality or flimsiness, notwithstanding the fact that the construction possesses adequate structural integrity in objective terms.
In an attempt to overcome this problem, it is known to construct wall sections by first forming a structural timber frame, erecting formwork around the frame, and filling the cavities around the frame members with mortar or concrete. The formwork is removed when the concrete has set sufficiently to be self-supporting, thereby providing a free standing structural wall formed substantially of concrete. The need for internal steel reinforcing may be obviated by the use of fibre reinforced cement cladding. In a variation on this method, permanent formwork can be made directly from fibre reinforced cement sheets.
While these techniques provide the desired feel of solidity and substantiality, they possess inherent disadvantages. The most significant problem is that because of the material costs, the relatively high labour content required, and the time involved, the technique is not cost effective in comparison with conventional masonry construction.
In an attempt to minimise the time involved in erecting the structural framework, as well as reducing material costs, it has been known to use steel framing elements, typically in the form of C-shaped channels, in domestic housing construction. It has been found, however, that conventional C-shaped steel framing sections exhibit a relatively low degree of torsional rigidity. Furthermore, it has been found that the fastening of internal lining and external cladding materials to steel framing elements of this type, can be problematic. In particular, if impact driven fasteners are used, there is a tendency for the flanges of the steel framing elements to bend inwardly, away from the facing sheet. This prevents penetration and secure engagement. The resultant buckling and warping, also reduces the structural strength and the dimensional accuracy of the framing structure. In such systems, it is therefore necessary to use self-drilling, self-tapping screws, which exert lower lateral forces on the framing elements during installation. However, this fastening technique is time consuming and expensive relative to impact driven fastener nails.
In an attempt to overcome some of these problems, it is known to produce steel framing members having boxed edge flanges. These are generally more resistant to bending in response to the application of lateral forces and exhibit greater torsional rigidity. However, while these conventional box flanged steel studs theoretically possess sufficient strength and rigidity to withstand fastening of cladding sheets with self piercing impact fasteners such as nails, the holes pierced by the fastener tend to be at least the same diameter as, and often marginally larger than, the fastener themselves. As a consequence, the pull-out strength of the joint is usually inadequate. Accordingly, the requirement for fastening of cladding sheets or boards by means of screws remains as a relatively time consuming and labour intensive part of the construction process.
Similar comments apply in respect of steel stud framing dry wall systems which are used primarily in the construction of commercial building to produce internal partition walls. In such wall structures, sheet cladding materials are secured, generally by the use of self-drilling, self-tapping screws, to internal steel stud wall frames. Thermal and/or acoustic insulating materials may also be provided within the cavity and single or multiple external layers of different sheet materials are used depending on the performance characteristics required for different applications. For example, where a fire rating is required, a gypsum wall board product will usually be incorporated, and where a hard abrasion resistant material is required the cladding may include a fibre reinforced cement sheeting such as the Villaboard(trademark) product produced by the applicant company.
As with the previously described solid composite wall structures, the screw fastening of the cladding materials to the metal studs makes the construction process very expensive due both to the material cost of the self-drilling, self-tapping screws and the time taken to assemble the structure using such fasteners.
It is an object of the present invention to overcome or substantially ameliorate at least some of the disadvantages of the prior art, or to provide a useful alternative.
Accordingly, in its broadest form the invention provides a method of partition construction, said method including the steps of erecting a support frame from spaced apart frame members having boxed mounting flanges, the frame members being formed from a metal having a relatively high tensile strength, applying a layer of sheet material to at least one side of the frame, and securing said layer of sheet material to the frame by means of self-piercing impact fasteners.
The term xe2x80x9cpartitionxe2x80x9d is used herein to include within its meaning structural load bearing or non-load bearing partitions including walls, floors and ceilings etc.
In the preferred embodiment, the frame members include studs each having spaced apart closed boxed mounting flanges joined by an intermediate web section. In other embodiments, the studs may be constructed from simple box sections without an intermediate web and as such may include standard square, rectangular or other hollow sections. Preferably such sections are modified to include two or more layers adjacent the mounting flanges.
Desirably, the frame members having boxed mounting flanges are configured to enable suitably sized self-piercing impact fasteners to penetrate two adjacent but spaced external and internal surfaces of the frame member. Preferably, the external surface of the frame member is configured to extend transverse to the direction of penetration of the self piercing impact fastener and the internal surface is inclined thereto. In this manner penetration of the fastener through the two layers enables the effect of the resilience of the high tensile material to be enhanced to further grip the impact fastener.
In one preferred form of the invention, the frame member has what is commonly referred to as a xe2x80x9cdog bonexe2x80x9d section as illustrated in the accompanying examples. In another preferred form, the frame member is similar to a standard Z-section member but includes closed-in outer box sections will also be described hereafter.
In preferred wall applications the frame members or studs are vertically oriented, and are joined by generally horizontal or inclined connecting members. Preferably, the connecting members include generally channel shaped top plates, and bottom plates.
Desirably, the frame members are between 50 mm and around 200 mm in width, and ideally about 70 mm to 90 mm in width, corresponding to the distance between the flanges and hence the thickness of the wall cavity. The stud spacing is preferably 300 mm to 600 mm centres and ideally around 400 mm centres.
In one preferred form of the invention, the self-piercing impact fasteners comprise nails which are preferably applied using a powered nail gun or driver. In another preferred form, a two-pronged self piercing impact fastener with bridging member, such as a staple, is used. The staple may be configured to penetrate one or more layers of the frame member. The staple may have the parallel prongs that extend transversely to the bridging member or may be configured to diverge on penetration. Desirably, the staples are also applied by use of a powered gun or driver.
In a first preferred application of the invention there is provided a method of construction of a solid filled partition, said method including the steps of erecting a support frame from spaced apart frame members having boxed mounting flanges, the frame members being formed from a metal having a relatively high tensile strength, applying an internal layer of sheet material to an inner side of the frame, applying an external layer of sheet material to an outer side of the frame, securing said internal and external layers of sheet material to the frame by means of self-piercing impact fasteners, and filling the wall cavity with a cementitious material.
Preferably, the frame member is of a structure in accordance with any one of the preferred forms outlined above.
More preferably, the frame members are formed from a high tensile sheet steel having a thickness of between 0.2 mm and 1.2 mm, and ideally between 0.35 mm and 1 mm. Preferably, the frame members have a yield strength of between 400 MPa and 700 MPa, and ideally around 550 MPa.
Desirably, the cementitious material preferably includes additives selected to provide an overall core density of between 200 kg/m3 and around 1200 kg/m3, and ideally about 550 kg/m3. Preferably, the cementitious material takes the form of a concrete formulation.
One preferred concrete formulation includes:
30% to 60% by weight of cement;
10% to 30% by weight of sand;
20% to 40% by weight of water;
1% to 10% by weight of expanded polystyrene beads; and
1% to 5% by weight of concrete additives.
It has been found that this composition produces the desired characteristics for the purpose in terms of pumpability, adequate stickiness and density, and acceptable cost.
Preferably, the cementitious material is applied by pumping or spraying.
In a preferred embodiment, the sheet material is a fibre reinforced cement sheet having a relatively low permeability. Alternatively, the sheet material may be a cement bonded particle board. In a preferred embodiment, a jointing compound is applied over abutting edges of adjacent sheets to conceal the joins.
In one preferred form the sheet material is secured to the frame members by self-piercing impact fasteners in the form of hardened nails that are ideally galvanised and have a knurled shank and which are preferably applied by a powered nail gun or driver. Sample wall specifications with cavity size, sheet specifications, nail specifications and nail spacing configurations are exemplified below.
In another preferred form, the sheet material is secured to the frame members by means of staples which are preferably steel galvanised and which are preferably applied by a powered nail gun or driver. Sample wall specifications with cavity size, sheet specifications, staple specifications and staple spacing configurations are exemplified below.
In accordance with a second preferred application of the invention there is provided a method of dry wall construction, said method including the steps of erecting a support frame from spaced apart frame members having boxed mounting flanges, the frame members being formed from a metal having a relatively high tensile strength, applying a layer of sheet material to at least one side of the frame, and securing said layer of sheet material to the frame by means of impact driven staples.
Preferably, the frame members are configured in accordance with one of the preferred frame structures outlined above.
More preferably, the frame members are formed from a high tensile sheet steel having a thickness of between 0.2 mm and 1.2 mm, and ideally between 0.35 mm and 1 mm. Preferably, the frame members have a yield strength of between 400 MPa and 700 MPa, and ideally around 550 MPa.
In one embodiment, straight parallel pronged staples may be used. In other embodiments, staples having diverging prongs or tines may be used to increase the pull-out strength of the joint.
Desirably, the method includes the step of controlling the penetration depth of the staple through the outer surface of the sheet material to simplify any subsequent finishing process that may be required. For example with fibre reinforced boards that will require finishing across the joins, the staples are set to recess below the outer surface so that filling and finishing is a relatively simple low skill task.
Depending on the application, the method of construction may include the step of securing a further layer of sheet material to the opposite side of the frame. As required, the method may also include the step of securing additional layers of sheet materials such as paper clad gypsum board and fibre reinforced sheeting depending on the application. Typical sample specification are exemplified below.
In another aspect the invention provides a partition constructed in accordance with any one of the various methods outlined above.